1. Field of the Invention
The present invention relates to a head suspension having a piezoelectric element that deforms in response to a voltage applied thereto and a method of manufacturing the head suspension.
2. Description of Related Art
Small-sized, precision information devices are rapidly advancing, and for use with such devices, needs for micro-actuators capable of conducting positioning control for very small distances are increasing. Such micro-actuators are highly needed by, for example, optical systems for correcting focuses and inclination angles, ink jet printers for controlling ink heads, and magnetic disk drives for controlling magnetic heads.
To meet the need for micro-actuators for magnetic disk drives, Japanese Unexamined Patent Application Publication No. 2002-184140 has proposed a head suspension for a disk drive. The head suspension includes a base plate, a hinge to form an actuator base with the base plate, a load beam provided with a flexure, and a piezoelectric actuator having a pair of piezoelectric elements. The piezoelectric actuator is fixed with an adhesive layer into an opening formed on the actuator base.
This related art employs a dual actuator system that uses, for a precise positioning purpose, a voice coil motor and the piezoelectric actuator having two piezoelectric elements made of, for example, PZT (lead zirconate titanate).
The piezoelectric actuator in the dual actuator system minutely moves a front end of the load beam in a widthwise direction (sway direction) of the head suspension. Compared with a single actuator system employing only the voice coil motor, the dual actuator system employing the voice coil motor and piezoelectric actuator is capable of more precisely positioning a magnetic head attached to a front end of the head suspension.
The head suspension of the dual actuator system is required to be thin to reduce an installation space. To meet the requirement, the base plate is preferably integrated with the actuator base.
Producing the integrated base plate and actuator base from a single material, however, increases cost.
Each piezoelectric element needs supply of electric power. For this, an electrode of the piezoelectric element must electrically be connected to the actuator base. This connection is achieved by placing a conductive material such as silver paste between the electrode of the piezoelectric element and the actuator base. To secure conductivity of the connection, a part of the actuator base where the conductive material is placed is plated with gold.
If the actuator base is separated from the base plate, the gold plating to the actuator base is easy to achieve. Namely, the actuator base will be manufactured by etching a thin material or a rolled material on which many actuator bases are patterned and chained together. During the etching stage of the thin or rolled material, the chained actuator bases are together masked and plated with gold.
If the actuator base is integral with the base plate, such a collective masking and plating process is impossible to achieve because a boss must be formed in the base plate and a burr removing process and a heat treatment must be carried out. These processes are hardly achievable on chained objects, and therefore, the integrated base plate and actuator base must be separated from the others before conducting the processes. Once separated, each integrated base plate and actuator base is in the size of, for example, several millimeters, and therefore, is difficult to partly mask and partially plate with gold. To avoid this difficulty, the integrated base plate and actuator base may entirely be plated with gold. This, however, increases cost.